The technique of stay-in-build insulating concrete forming systems for joisted concrete floors employing channeled panels of expanded plastic associated with reinforcement steel bars of load bearing ribs, realized upon the consolidation of poured concrete filling channels defined in the expanded plastic panels for accommodating reinforcement bar fabrics is well-known and commonly practiced in the concrete building industry.
The publications WO 2005/108700-A1 and WO 2005/121467 A2, both to Cretti and assigned to the assignee of this application, disclose significant examples of such a technique for constructing floors as an alternative to the traditional technique employing pre-fabricated load bearing reinforced concrete beams and bridging hollow floor bricks laid there between.
The high degree of automation that is practicable in producing panels of expanded plastic, metal elements of self standing and/or reinforcement steel bar fabrics for the concrete ribs to be formed, the lightness of the expanded plastic panels compared to the traditional materials used for constructing floor such as pre-fabricated reinforced concrete beams and hollow floor bricks, significantly reduce the costs of transportation and for laying the panels and the reinforcement steel bar fabrics over which concrete is eventually poured. This technique simplifies the construction of floors at sensibly reduced cost and enhances acoustic and thermal isolation characteristics.
Labor cost in laying the expanded plastic panels and the reinforcement metal structures (fabrics) into channels defined in the expanded plastic panels and of eventual other metallic elements for providing adequate self-standing properties of the laid panels and reinforcement structures onto which the concrete will be poured and evenly distributed, remains yet an important cost factor. Moreover, assembling and laying the distinct components at the construction site may lead to assembly imprecision that could, in the worst case, determine instability of the reinforcement metal structures within the channels defined in the body of the expanded plastic panels, during the distribution of the poured concrete.
Notably, floors constructed with this technique have a reduced ability to retard penetration of flames in the finished floor structure because of an excessive contraction of the expanded plastic bodies caused by a prolonged exposure to strong heat may lead to the peeling off of plaster coats or the falling off of the plaster boards or of other facing layer of the underside ceiling.
It is important that in case of fire, notwithstanding the fact that the expanded plastic may shrink as far as forming informal masses of reduced volume, the coats or facings of the underside ceiling, for example one or more layers of plaster or a facing of plaster boards remain in place, for retarding penetration of flames.